Enhancing exposure depth for surface-plasmon polaritons interference nanolithography by waveguide modulation

A maskless interference device with a waveguide coated thin metal film is investigated for surface-plasmon polaritons interference lithography (SPPIL) in this paper. The focal depth of interference fringes in the resist is modulated obviously by the thicknesses of the waveguide and the metal film, which will solve the question of short exposure depth for conventional SPPIL, and improve the practicability of SPPIL. Simulated and analyzed results demonstrated that the focal depth of interference fringes is increased dramatically with suitable parameters for the structure. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3330697]